(1) Field of the Invention
The present invention relates to a power steering system and a control apparatus for the power steering system. The power steering system provides a steering assistance force for a steering mechanism with an electrically driven motor as a drive source.
(2) Description of Related Art
As is well known, a power steering system detects a steering angle of a steering wheel from a neutral state of the steering wheel and transmits a torque to a steering mechanism of the vehicle from an electrically driven motor on a basis of the detected steering angle to perform an assistance of the steering.
In the power steering system, the steering angle signals calculated in a main calculation section and in a sub calculation section are compared with each other to determine the abnormality on the calculation of the steering angle.
A Japanese Patent Application First Publication No. Heisei 6-239261 published on Aug. 30, 1994 (which corresponds to a U.S. Pat. No. 5,504,679 issued on Apr. 2, 1996) exemplifies a previously proposed steering system in which the steering angle signals of single core CPUs which are mutually physically separated from each other are compared with each other to determine the abnormality. It should be noted that CPU is an abbreviation for Central Processing Unit.